This invention relates to phased array radar systems and more particularly to radar systems of the type employing a plurality of antenna elements disposed in a linear, rectangular or other ordered array, so as to establish a narrowly directive sensitivity pattern in the desired direction of transmission or reception of electromagnetic wave energy. Still more particularly, this invention is directed to electronic scanning means for use with phased array antenna systems, enabling the forming and steering of one or a plurality of individual transmit and receive beams with good precision of control of beam direction and with a minimum of system and component complexity.
In prior art phased array radar systems the phase commands or control signals for adjusting the relative phases of the individual array elements as necessary to form and steer the beams formed by the array have been generated and applied to the antenna elements in many different ways. Perhaps most commonly, phase command signals have been generated in general purpose computers using algorithms or equations which are now well known in the art for computing the values of phase weightings necessary to achieve the desired array beam positions. Beam control in this manner may require the dedication of a fairly sizable data processor simply to compute and supply the proper phase commands, particularly if more than one beam is to be formed simultaneously, and systems of this kind accordingly tend to be somewhat complex and correspondingly costly to manufacture and maintain. Also, with digital systems it commonly is the practice to employ digital phase shifters and to quantize or round off the calculated phase commands to perhaps three or four bits, and unless the round-off errors thus introduced are carefully compensated the resultant accuracy may suffer accordingly.
Other proposals for more direct and simplified generation of the array element phase commands have involved use of electro-optical processors of various kinds, one such system, by way of example, being described and claimed in the copending application of Fitelson et al, Ser. No. 800,155, filed May 25, 1977, of common ownership herewith. Phase command generators have also been implemented in a variety of other circuit configurations such as disclosed, for example, in U.S. Pat. Nos. 3,450,145 to Johnson and 4,112,430 to Ladstatter, also of common ownership herewith.
The present invention is directed to electronically scanned arrays which are of the general kind described in these earlier patents, but which afford different or additional capabilities and advantages in areas of system performance, complexity and cost. To these ends, the array phase command generating system of the present invention utilizes charge transfer device (CTD) complex matrix multipliers such as disclosed in U.S. Pat. Nos. 4,156,284 to Engeler and 4,161,785 to Gasparek, both of common assignment with the present application, in a particularly cost-effective combination in which the array is capable of forming and steering either a single beam or a plurality of beams simultaneously with good accuracy and precision of control, and without limitation to specific angles in space, all with minimized complexity and cost of system implementation.